Format

Send to

Choose Destination
J Physiol. 2006 Aug 1;574(Pt 3):905-15. Epub 2006 Feb 23.

The rate of heat storage mediates an anticipatory reduction in exercise intensity during cycling at a fixed rating of perceived exertion.

Author information

1
University of Cape Town Medical Research Council (UCT/MRC) Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, South Africa. rtucker@sports.uct.ac.za

Abstract

The aim of the present study was to examine the regulation of exercise intensity in hot environments when exercise is performed at a predetermined, fixed subjective rating of perceived exertion (RPE). Eight cyclists performed cycling trials at 15 degrees C (COOL), 25 degrees C (NORM) and 35 degrees C (HOT) (65% humidity throughout), during which they were instructed to cycle at a Borg rating of perceived exertion (RPE) of 16, increasing or decreasing their power output in order to maintain this RPE. Power output declined linearly in all three trials and the rate of decline was significantly higher in HOT than in NORM and COOL (2.35 +/- 0.73 W min(-1), 1.63 +/- 0.70 and 1.61 +/- 0.80 W min(-1), respectively, P < 0.05). The rate of heat storage was significantly higher in HOT for the first 4 min of the trials only, as a result of increasing skin temperatures. Thereafter, no differences in heat storage were found between conditions. We conclude that the regulation of exercise intensity is controlled by an initial afferent feedback regarding the rate of heat storage, which is used to regulate exercise intensity and hence the rate of heat storage for the remainder of the anticipated exercise bout. This regulation maintains thermal homeostasis by reducing the exercise work rate and utilizing the subjective RPE specifically to ensure that excessive heat accumulation does not occur and cellular catastrophe is avoided.

PMID:
16497719
PMCID:
PMC1817748
DOI:
10.1113/jphysiol.2005.101733
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center